This K01 Mentored Research Scientist Development Award proposal describes a rigorous five year training program in genetic epidemiology with an emphasis on eating disorders. Eating disorders are often chronic, and have severe medical, psychological, and financial consequences for patients and their families. However, many questions about their etiology remain. Recently, investigators have begun to examine the role of genetics in the development of eating disorders. Yet, the relative contributions of genetic and environmental factors to eating disordered behaviors require further investigation in order to enhance prevention and treatment efforts. This application outlines a training program that will enable Dr. Mazzeo to combine her previous experience in eating disorders research, and her strong background in psychometrics,with skills in genetics, epidemiology, and biostatistics. These skills will be applied in a series of population based twin studies examining the role of both genes and environment in the development and maintenance of the full range of eating problems. The general goals of this research program are to increase our understanding of the heritabUity of specific disordered eating behaviors, and to enhance knowledge of environmental factors that lead to gene expression among individuals biologically predisposed to eating problems. Specific research objectives include: a) conducting a meta-analysis of previous investigations of the heritability of bulimia nervosa and associated symptomatology in twins; b) examining the influence of genetic and environmental factors on dietary restraint, disinhibition, and susceptibility to hunger; c) testing the validity of the equal environment assumption in both U.S. and Norwegian twin samples using contextual variables that are particularly relevant to the development of eating pathology; d) evaluating the role of constitutional thinness as a protection against the development of eating disorders in men, e) testing explanatory models of the comorbidity of eating and alcohol use disorders, and eating and mood disorders in a population-based twin sample of men; and f) evaluating models of the comorbidity of eating and anxiety disorders, and eating and alcohol use disorders in a population-based twin sample of women. Completion of this training program will enable Dr. Mazzeo and her sponsors to elucidate genetic and environmental risk factors for eating disorders. It will also provide Dr. Mazzeo with the requisite training to become an independent investigator in the genetic epidemiology of eating disorders.